Central Processing Unit
The microprocessor is an important component in the CPU. It is the unit which processes the instructions depending on its capability to process. The latest processors like Pentium etc. process the information at very high speeds i.e., the time taken to complete one instruction is very small.
Mother board is a printed circuit board on which various components including the microprocessor(s) is placed on. Provision to attach additional cards like video display unit controller card, floppy and hard disk controller card, memory, the input and output ports etc., will be provided. Additional slots to add more cards like Audio and Video cards, internal modem card, additional memory etc., are also provided.
Random Access Memory (RAM)
This memory is used by the Central Processing Unit to do all calculations and temporarily store the data. It can also be used as a scratch area for microprocessor. This memory is volatile, i.e. whenever the computer is switched off, or during the power failure, the data in this memory is lost. Therefore the output of the process is stored in secondary storage like Hard Disk or Floppy Disk etc.
Read Only Memory (ROM)
This type of memory is required for many purposes. For example, a ROM chip called BIOS (Basic Input Output System) checks whether all the peripherals and components of a computer are in working condition, before handing over the control to the operating system and then to the user, whenever a computer is switched on. This memory does hold some data, which is not erasable even during the power failure.
Video Display Unit Controller Card
(A card means a Printed Circuit Board, which electronic components soldered to it). These cards control the video display unit. This is a principle part which helps the display of data on the monitor. There are various types of Video Display Unit Controller cards.
Disk Controller Card
These cards control the Floppy Disk Drives , Hard Disk Drives and CD-ROM drives. There are various types of Disk Controller Cards.
Audio and Video Controller Cards
These cards control the audio and video equipment attached to the computer for multimedia applications. There are various types of cards available.
Internal Modem Card
These cards are used for sending and receiving information through telephone lines as well as connecting to a main computer from a different location. This card is used in sending e-mail.
Switch Mode Power Supply (SMPS)
This is the unit which supplies regulated power supply to the components of the computer.
Secondary Storage Devices
The storage of the data on secondary storage device of the computer is measured in terms of bytes. A byte consists of 8 characters. A KiloByte (KB) consists of 1024 bytes. A MegaByte (MB) consists of 1024 KiloBytes. A GigaByte (GB) consists of 1024 MegaBytes. In other word a GigaByte consists of 1.08 billion bytes approximately.
Floppy Disks and Hard Disks
These disks can be used as input as well as output devices. The data for processing (input) or results of the program (output) can be stored for future reference and hence called Secondary Storage. (Primary Storage means the data stored in the main memory of a CPU) These disks contain a magnetic disk(s) on which the data is written by a magnetic head. The access time of the hard disk is very fast as the data is accessed randomly. Any part of the magnetic disk is accessed by the magnetic head at any point of time.
The magnetic tapes are generally used as a backup device. The data stored on the Hard disk is backed up on the magnetic tape. The access of the data from a magnetic tape is very slow when compared to the access time of the Hard disk. This is due to the fact that the data accessed is sequential. If the data required is at the end of the tape, the tape has to unwound till the end.